Sewing machine

ABSTRACT

A lower end of a thread guide lever, which is rockably attached to a lower looper and supports a thread pipe, and an air ejecting unit, which faces a thread inserting hole of the thread pipe and ejects air toward the thread inserting hole, are coupled via a coupling member so that they are interlocked with each other. The coupling member is moved such that a discharging port of an air nozzle is positioned at an ejecting position close to the thread inserting hole when a thread discharging hole is positioned at a threading position which is coincident with a thread hole of a lower looper, and such that the air nozzle is moved to a standby position when the thread discharging hole is moved to a retreating position.

The present invention claims priority from Japanese Patent Application No. 2006-218233 filed on Aug. 10, 2006, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a sewing machine having a threading device for inserting a thread through a looper.

BACKGROUND ART

Some sewing machines, such as an over-edge overlock sewing machine and a double chainstitch sewing machine, has a threading device for inserting a thread through a looper by utilizing pressurized air (see, e.g., JP 2005-318932 A). As shown in FIGS. 11 to 13, such a threading device includes a lower looper driving mechanism 500 having a lower looper 510. The lower looper 510 has an extended portion 510 a which is inserted into a loop of a needle thread by moving the extended portion 510 a back and forth in synchronization with a vertical motion of a needle. The threading device further includes a thread pipe 520, a thread guide lever 530 which moves the thread pipe 520, an air ejecting unit 540, and an air pump 550 which supplies air to the air ejecting unit 540. The thread pipe 520 has one end serving as a thread inserting hole 521, the other end serving as a thread discharging hole 522, and a thread path inside which a lower looper thread T is inserted. The thread guide lever 530 moves the thread pipe 520 such that the thread discharging hole 522 is moved between a threading position, at which the thread discharging hole 522 and a thread hole 510 b of the looper 510 becomes coincident, and a retreating position, which is placed apart from the threading position. The air ejecting unit 540 is disposed so as to face the thread inserting hole 521 and ejects the air toward the thread inserting hole 521.

When inserting the lower looper thread T through the thread hole 510 b of the lower looper 510, the thread discharging hole 522 of the thread pipe 520 is caused to be coincident with the thread hole 510 b of the lower looper 510, and pressurized air is then ejected toward the thread inserting hole 521 of the thread pipe 520.

Meanwhile, when changing the lower looper thread T in a threading device of a sewing machine disclosed in JP 2005-318932 A, firstly, a mark m1 on a flywheel 507 is adjusted to a mark m2 on a sewing machine frame M to place the lower looper 510 at its rocking end position. Then, the thread guide lever 530 is moved in a direction of an arrow A (see FIG. 12) to cause the thread discharging hole 522 of the thread pipe 520 and the thread hole 510 b of the lower looper 510 to be coincident (see FIG. 13). Subsequently, an operation lever 4 of the air ejecting unit 540 is moved in a direction of an arrow C shown in FIG. 11 to move an outlet 541 a of an air nozzle 541 toward the thread inserting hole 521, and the air pump 550 is thereafter operated to eject the compressed air, thereby inserting the lower looper thread T through the thread hole 510 b of the lower looper 510. After the lower looper thread T is inserted, moreover, it is necessary to first move the operation lever 4 in a direction of an arrow D as shown in FIG. 11 and to then move the thread guide lever 530 in a direction of an arrow B as shown in FIG. 13. Thus, there is a problem that such a operation for changing the lower looper thread T is complicated because many portions needs to be operated. Furthermore, there is a problem that a great deal of time and labor is required for the operation because the operation needs to be carried out in accordance with a certain procedure.

SUMMARY OF THE INVENTION

It is an object of the invention to facilitate a changing operation of a looper thread.

According to one or more aspects of the invention, a sewing machine comprises:

a looper driving mechanism including a looper, wherein the looper is formed with a thread hole at a tip portion thereof, and the tip portion of the looper is adapted to be inserted into a loop of a needle thread by moving the tip portion back and forth in synchronization with a vertical motion of a needle;

a thread path member having one end formed with a thread inserting hole, the other end formed with a thread discharging hole, and a thread path inside which a lower looper thread is able to be inserted;

thread path member moving means for moving the thread path member such that the thread discharging hole is moved between a threading position, at which the thread discharging hole becomes coincident with the thread hole of the looper, and a retreating position placed apart from the threading position;

air ejecting means for ejecting air toward the thread inserting hole, wherein the air ejecting means is disposed so as to face the thread inserting hole;

air supplying means for supplying the air to the air ejecting means;

air ejection moving means for moving the air ejecting means between an ejecting position adjacent to the thread inserting hole and a standby position placed apart from the ejecting position; and

interlocking means for interlocking the thread path member moving means and the air ejection moving means such that the air ejecting means is positioned at the ejecting position when the thread discharging hole is positioned at the threading position.

According to one or more aspects of the invention, the interlocking means includes:

a first actuator which drives the thread path member moving means;

a second actuator which drives the air ejection moving means; and

interlocking control means for driving the first and second actuators such that the thread path member moving means and the air ejection moving means synchronize with each other.

According to one or more aspects of the invention, the interlocking means includes a coupling member which couples the thread path member moving means and the air ejection moving means.

According to one or more aspects of the invention, the interlocking means includes an actuator which drives at least one of the thread path member moving means and the air ejection moving means.

According to one or more aspects of the invention, wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle,

wherein the sewing machine further comprises:

input means for inputting an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper;

spindle angle detecting means for detecting that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and

ejection control means for stopping the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting means and for driving the actuator to position the air ejecting means at the ejecting position when the instruction to start the threading operation is input from the input means.

According to one or more aspects of the invention, the sewing machine further comprises returning means for positioning the thread discharging hole of the thread path member at the retreating position in accordance with a drive of a sewing machine motor.

According to one or more aspects of the invention, a sewing machine comprises:

a looper driving mechanism including a looper, wherein the looper is formed with a thread hole formed at a tip portion thereof, and the tip portion of the looper is adapted to be inserted into a loop of a needle thread by moving the tip portion back and forth in synchronization with a vertical motion of a needle;

a thread pipe having a thread path inside which a lower looper thread is able to be inserted, wherein the thread path connects a thread inserting hole and a thread discharging hole, and the thread pipe is arranged such that the thread discharging hole is movable between a threading position a threading position, at which the thread discharging hole becomes coincident with the thread hole of the looper, and a retreating position placed apart from the threading position;

a thread pipe moving mechanism which is coupled to the thread pipe and is operable to move the thread discharging hole between the threading position and the retreating position;

an air ejecting unit which is movable between an ejecting position, at which the air ejecting unit faces the thread inserting hole and ejects air toward the thread inserting hole, and a standby position placed apart from the ejecting position;

an air supplying unit which supplies the air to the air ejecting unit;

a air ejection moving mechanism which is coupled to the air ejecting unit, and operable to move the air ejecting unit between the ejecting position and the standby position; and

an interlocking mechanism operable to interlock the thread pipe moving mechanism and the air ejection moving mechanism such that the air ejecting unit is moved from the standby position to the ejecting position when the thread discharging hole is moved from the retreating position to the threading position.

According to one or more aspects of the invention, the interlocking mechanism includes:

a first actuator which drives the thread pipe moving mechanism;

a second actuator which drives the air ejection moving mechanism; and

an interlocking control portion operable to drive the first and second actuators such that the thread pipe moving mechanism and the air ejection moving mechanism synchronize with each other.

According to one or more aspects of the invention, the interlocking mechanism includes a coupling member which couples the thread pipe moving mechanism and the air ejection moving mechanism.

According to one or more aspects of the invention, the interlocking mechanism includes an actuator which drives at least one of the thread pipe moving mechanism and the air ejection moving mechanism.

According to one or more aspects of the invention, wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle,

wherein the sewing machine further comprises:

an input portion form which an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper is input;

a spindle angle detecting sensor which detects that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and

an ejection control portion which stops the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting sensor and drives the actuator to position the air ejecting unit at the ejecting position when the instruction to start the threading operation is input from the input portion.

According to one or more aspects of the invention, the sewing machine further comprises a guide member which positions the thread discharging hole at the retreating position in accordance with a drive of a sewing machine motor.

According to one or more aspects of the invention, when the thread path member (the thread pipe) is moved to the threading position by the interlocking means (the interlocking mechanism), the air ejecting means (the air ejecting unit) is moved to the ejecting position. Similarly, when the air ejecting means (the air ejecting unit) is moved to the ejecting position, the thread path member (the thread pipe) is moved to the threading position. Namely, when one of the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) is operated, the other is also operated at the same time. Consequently, the operation for inserting the thread through the looper is simplified than the background art. In addition, a certain operating procedure is not required. Therefore, the threading operation can easily be carried out. As a result, it is possible to enhance an operability of the sewing machine.

According to one or more aspects of the invention, the thread path member moving means (the thread pipe moving mechanism) is driven by the first actuator and the air ejection moving means (the air ejection moving mechanism) is driven by the second actuator. Moreover, the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are driven by the interlocking control means (the interlocking control portion) such that mutual operating directions are coincident with each other. Namely, the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are electrically interlocked with each other. Accordingly, it is possible to automatically position the thread discharging hole of the thread path member (the thread pipe) at the threading position. Thus, it is possible to easily insert the lower looper thread into the looper. Furthermore, it is also possible to automatically position the thread discharging hole of the thread path member (the thread pipe) at the retreating position. Moreover, it is possible to interlock the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) without directly connecting them mechanically. Therefore, it is possible to enhance a degree of freedom of the arrangement in the sewing machine.

According to one or more aspects of the invention, the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are mechanically connected, and are interlocked by the coupling member. Therefore, the cost can be reduced due to a simple structure.

According to one or more aspects of the invention, it is possible to electrically control the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) by driving the actuator, and to control their driving operations at the same time through the coupling member.

Namely, it is possible to electrically control the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) while reducing a cost by using one actuator and the coupling member. In addition, the detecting means (the detecting sensor) may be provided to detect that the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are positioned at predetermined positions. In such as case, it is possible to control the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) to be automatically stopped at the predetermined positions.

According to one or more aspects of the invention, the ejection control means (the ejection control portion) stops the spindle at the predetermined rotating angle based on the detection of the spindle angle detecting means (the spindle angle detecting sensor) and drives the actuator to position the air ejecting means (the air ejecting unit) at the ejecting position when the instruction to start the threading operation for inserting the lower looper thread through the looper is input from the input means (input portion), whereby the thread discharging hole of the thread path member (the thread pipe) is positioned at the threading position. Accordingly, it is possible to easily carry out the threading work for inserting the thread through the looper. Thus, it is possible to enhance an operability of the sewing machine.

The “predetermined rotating angle” may be an angle of the spindle angle at which the looper, which is rocked interlockingly with the spindle, is positioned at one end of its rocking motion, and the “predetermined rotating angle” can be set to be a desirable rotating angle.

According to one or more aspects of the invention, the thread discharging hole of the thread path member (the thread pipe) is positioned at the retreating position in accordance with the driving operation of the sewing machine motor by the returning means (the guide member). Moreover, the air ejecting means (the air ejecting unit) is positioned at the standby position via the interlocking means (the interlocking mechanism). Consequently, it is possible to smoothly make a transition to the sewing operation even in a case where a user forgets to return the thread discharging hole of the thread path member (the thread pipe) to the retreating position after inserting the lower looper thread through the thread hole of the looper. In other words, the user of the sewing machine does not need to return the thread discharging hole of the thread path member (the thread pipe) from the threading position to the retreating position after inserting the thread through the looper. Consequently, it is possible to easily carry out the work for inserting the thread through the looper. As a result, it is possible to enhance the operability of the sewing machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a sewing machine according to a first exemplary embodiment of the invention;

FIG. 2 is an enlarged view of an portion I shown in FIG. 1, illustrating a state in which a thread discharging hole of a thread pipe is moved to a threading position and an air nozzle is moved to a ejecting position;

FIG. 3 is an exploded perspective view showing an interlocking mechanism according to the first exemplary embodiment;

FIG. 4 is a schematic view showing a coupling structure of a thread guide lever and an air ejecting unit according to the first exemplary embodiment (the thread discharging hole of the thread pipe is at a retreating position);

FIG. 5 is another schematic view showing the coupling structure of the thread guide lever and the air ejecting unit according to the first exemplary embodiment (the thread discharging hole of the thread pipe is at the threading position);

FIG. 6 is an exploded perspective view showing an interlocking mechanism according to a second exemplary embodiment of the invention;

FIG. 7 is a schematic view showing a spindle angle detecting sensor employed in a sewing machine according to the second exemplary embodiment;

FIG. 8 is a block diagram showing a configuration of a control portion according to the second exemplary embodiment;

FIG. 9 is a flowchart showing an operation of the sewing machine according to the second exemplary embodiment;

FIG. 10 is a schematic view showing another exemplary embodiment of the invention in which a threading device includes returning means;

FIG. 11 is a schematic side view of a sewing machine according to the background art;

FIG. 12 is a side view showing a threading device of the sewing machine according to the background art (a thread discharging hole of a thread pipe is at a retreating position);

FIG. 13 is another side view showing the threading device of the sewing machine according to the background art (the thread discharging hole of the thread pipe is a threading position);

FIG. 14 is a schematic view showing a driving structure of a thread guide lever according to a third exemplary embodiment of the invention;

FIG. 15 is a schematic view showing a driving structure of an air ejecting unit according to the third exemplary embodiment; and

FIG. 16 is a block diagram showing a structure of an interlocking control portion according to the third exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the invention will be described in detail with reference to FIGS. 1 to 10 and 14 to 16. In the exemplary embodiments, description will be given by taking an over-edge sewing machine as an example of a sewing machine.

In the following description, a Z-axis direction (an up-and-down direction) is a vertical direction, a Y-axis direction (a right-and-left direction) is a longitudinal direction of an arm portion of a sewing machine 1 placed on a horizontal plane, and an X-axis direction (a front-and-rear direction) is a longitudinal direction is a direction orthogonal to the Y-axis direction and is parallel to a surface of a throat plate (not shown). The X-axis direction, the Y-axis direction and the Z-axis direction are orthogonal to each other.

First Exemplary Embodiment Whole Structure

As shown in FIG. 1, the sewing machine 1 (an over-edge sewing machine) includes a needle driving mechanism (not shown) which vertically moves a needle 3 by driving a sewing machine motor 5 (see FIGS. 7 and 8), a lower looper driving mechanism 20 (a looper driving mechanism) having a lower looper 21, and an upper looper driving mechanism 10 having an upper looper 11. The lower looper 21 has an extended portion 21 a which is moved back and forth in synchronization with a vertical motion of the needle 3, thereby being inserted through loops of needle threads T1, T2 below a cloth (a workpiece) (see FIG. 4), while the upper looper 11 is operable to insert an upper looper thread through a loop of a lower looper thread T. The threads are sequentially entangled with each other by the needle 3, the lower looper 21 and the upper looper 11, whereby an over-edge sewing is carried out over the cloth. The sewing machine 1 further includes a threading device 100 which is operable to insert the lower looper thread T through a thread hole 21 b of the lower looper 21. Each of the portions will be described below in detail.

(Needle Driving Mechanism)

The needle driving mechanism (not shown) includes an upper shaft (not shown) which is rotated by driving the sewing machine motor 5, and a transmitting mechanism (not shown) which converts a rotation of the upper shaft into a vertical motion and transmits the vertical motion to a needle bar 2 via a rotating weight and a crank rod. Two needles 3, 3 are held at a lower end of the needle bar 2. Accordingly, when the upper shaft is rotated, the vertical motion is applied to the needle bar 2 through the transmitting mechanism so that the needles 3, 3 are vertically moved.

(Upper Looper Driving Mechanism)

The upper looper driving mechanism 10 includes an upper looper holding member 12 which holds the upper looper 11, a support member 13 which supports the upper looper holding member 12 in such a way as to allow a linear motion of the upper looper holding member 12 as well as rotations of the upper looper holding member 12 around two axes, and an operating mechanism 14 which reciprocates its coupling point to the upper looper holding member 12 between two positions. The upper looper holding member 12 is a round bar member, and holds the upper looper 11 at an end (an upper end) thereof. The upper looper 11 passes through a rear side of a moving locus of the lower looper 21 to insert the upper looper thread through the loop of the lower looper thread T, and a tip portion of the upper looper 11 moves to needle dropping points of the needles 3, 3, the needles 3, 3 and the needle threads T1, T2 (see FIG. 4) are inserted through a loop of the upper looper thread.

(Lower Looper Driving Mechanism)

The lower looper driving mechanism 20 is disposed below a throat plate (not shown), and includes a lower looper driving shaft 22 (a looper shaft) which is rotatably supported on a sewing machine frame M along the front-and-rear direction, a lower looper holding arm 23 which is fixed at a tip portion of the lower looper driving shaft 22 and carries out a rocking motion, and a lower looper 21 held at a rocking end portion of the lower looper holding arm 23. Although it is not shown in the drawings, there is provided a transmitting mechanism which converts a rotating force of a lower shaft 6 into a reciprocating rotating force, and applies the reciprocating rotating force to the lower looper driving shaft 22.

The lower looper driving shaft 22 carries out a reciprocating rotation in synchronization with the lower shaft 6, thereby rocking the lower looper holding arm 23. Accordingly, the lower looper 21 is moved below the throat plate so as to pass through a rear side of a moving locus of the needles 3, 3 in the vicinity thereof. Namely, the lower looper 21 is driven by a driving force from the sewing machine motor 5 via the lower looper driving shaft 22 which interlocks with the lower shaft 6. The lower looper 21 has the extended portion 21 a. The extended portion 21 a catches the loops of the needle threads T1, T2 inserted through the needles 3, 3 that are moved downward, and inserts the loop of the lower looper thread T through the loops of the needle threads T1, T2.

As shown in FIGS. 4 and 5, the extended portion 21 a is formed with the thread hole 21 b through which the lower looper thread T discharged from a thread discharging hole 112 of a thread pipe 110 is inserted. The extended portion 21 a is further formed with a looper groove 21 c which extends from the thread hole 21 b to a portion facing the retreating position of the thread discharging hole 112. The looper groove 21 c prevents a rotation of a thread guide lever 121 from being blocked due to the lower looper thread T discharged from the thread discharging hole 112 and interposed between the lower looper 21 and the thread guide lever 121.

A flywheel 7 positioned on an outer side of the sewing machine frame M is fixed to one end of the lower shaft 6. Thus, the flywheel 7 and the lower shaft 6 are integrally rotated together. A mark m1 is provided on the flywheel 7. When the mark m1 is coincident with a mark m2 provided on the sewing machine frame M, the lower looper 21 is positioned at one of its rocking end positions in the rocking motion (i.e. a rightmost end position shown in FIG. 1).

(Threading Device)

Next, the threading device 100 according to the first exemplary embodiment will be described in detail.

The threading device 100 inserts the lower looper thread T led from a thread groove 17 formed on the sewing machine frame M through the thread hole 21 b of the lower looper 21, and is disposed below the needle bar 2.

As shown in FIGS. 1 to 5, the threading device 100 includes the thread pipe 110. The thread pipe 110 has one end formed with a thread inserting hole 111, the other end formed with the thread discharging hole 112, and a thread path inside which the lower looper thread T is able to be inserted. The threading device further includes a thread pipe moving mechanism 120 (thread pipe moving means) operable to move the thread pipe 110 such that the thread discharging hole 112 is moved between the threading position, at which the thread discharging hole 112 is coincident with the thread hole 21 b of the lower looper 21 (see FIG. 5), and the retreating position placed apart from the threading position (see FIG. 4). The threading device further includes an air ejecting unit 130 (air ejecting means) which faces the thread inserting hole 111 and ejects air toward the thread inserting hole 111, an air pump 140 (air supplying means) which supplies the air to the air ejecting unit 130, an air ejection moving mechanism 150 (air ejection moving means) operable to move the air ejecting unit 130 between an ejecting position, which is close to the thread inserting hole 111, and a standby position placed apart from the ejecting position, and an interlocking mechanism 160 (interlocking means) operable to interlock the thread pipe moving mechanism 120 and the air ejection moving mechanism 150 such that the air ejecting unit 130 is positioned at the ejecting position when the thread discharging hole 112 of the thread pipe 110 is positioned at the threading position.

(Thread Guiding Means)

As shown in FIGS. 4 and 5, the thread pipe 110 is provided in parallel with a plane within which the lower looper 21 is rocked below the needle bar 2. The thread pipe 110 is a tubular member bent at two portions, and is formed into an almost C shape when seen from a side. As shown in FIG. 4, one end of the thread pipe 110 functions as the thread inserting hole 111 from which the lower looper thread T is inserted, and a diameter of the thread inserting hole 111 is increased toward an end thereof. Thus, the lower looper thread T can be inserted easily. As shown in FIG. 5, the other end of the thread pipe 110 functions as the thread discharging hole 112 from which the lower looper thread T is discharged, and a end portion of the thread discharging hole 112 is bent at an almost right angle. Namely, the thread pipe 110 functions as thread guiding means for guiding the lower looper thread T to the thread hole 21 b of the lower looper 21. The thread pipe 110 is connected to the thread pipe moving mechanism 120 so that the thread discharging hole 112 can be moved between the threading position, at which the thread discharging hole 112 becomes coincident with the thread hole 21 b of the lower looper 21 (the position shown in FIGS. 2 and 5), and the retreating position placed apart from the threading position (the position shown in FIGS. 1 and 4).

(Thread Pipe Moving Means)

The thread pipe moving mechanism 120 includes the thread guide lever 121 which supports the thread pipe 110 at an upper end thereof, the upper end being able to reciprocate between the threading position and the retreating position by a rocking motion, a thread guide lever base 122 which supports an intermediate portion of the thread guide lever 121 such that the thread guide lever 121 can be rotated, and a switching lever 123 which couples an end portion of the thread guide lever 121 and the thread guide lever base 122, and rocks the thread guide lever 121 thereby switching a position of the thread discharging hole 112 between the threading position and the retreating position.

The thread guide lever 121 is formed from a plate member such that one end and the other end are curved in opposite directions to each other. The thread guide lever 121 formed with a slot 121 a at an middle potion thereof, and is rotatably engaged with the thread guide lever base 122 by means of a fulcrum shaft 122 a penetrating through the slot 121 a. The other end of the thread pipe 110 is attached to one end of the thread guide lever 121 (the upper end in FIGS. 1 to 5) so as to penetrate the thread guide lever 121, and functions as the thread discharging hole 112. A portion of the thread pipe 110 near the thread inserting hole 111 is fixed at an intermediate portion of the thread guide lever 121 by bonding means such as an adhesive or a solder. A coupling hole 121 b is formed at the other end of the thread guide lever 121, and the thread guide lever 121 and the switching lever 123 is coupled via the coupling hole 121 b.

The thread guide lever base 122 is formed from a plate member, and is detachably attached to the lower looper holding arm 23 supporting the lower looper 21. The lower looper holding arm 23 supports the lower looper 21 at one end and is connected to the lower looper shaft 22, which rotates the lower looper 21, at the other end. Namely, the thread pipe moving mechanism 120 is detachably attached with respect to the lower looper 21. As a matter of course, the thread pipe 110 of the thread pipe moving mechanism 120 is detachably attached to the lower looper 21.

The fulcrum shaft 122 a is formed at one end of the thread guide lever base 122 so as to protruded toward the thread guide lever 121, and serves as a fulcrum of the rotation of the thread guide lever 121. The fulcrum shaft 122 a is engaged with the slot 121 a of the thread guide lever 121. A rotating shaft 122 b is formed at the other end of the thread guide lever base 122, and rotatably supports the switching lever 123.

The switching lever 123 is formed from a plate member and is disposed between the thread guide lever 121 and the thread guide lever base 122. An inserting hole 123 a is formed on one end of the switching lever 123, and the rotating shaft 122 b is inserted into the inserting hole 123 a, whereby the switching lever 123 is rotatable with respect to the rotating shaft 122 b. A coupling shaft 123 b is formed on the other end of the switching lever 123, and is inserted into the coupling hole 121 b of the thread guide lever 121 so that the switching lever 123 is rotatably coupled to the thread guide lever 121. According to the first exemplary embodiment, the coupling shaft 123 b is protruded in the X-axis direction, that is, toward front side of the papers of FIGS. 4 and 5, and is inserted in a coupling groove 161 a of a coupling member 161 which will be described below (see FIGS. 4 and 5).

(Air Ejecting Means)

The air ejecting unit 130 includes a base 131 which is movable between an ejecting position close to the thread inserting hole 111 (the position shown in FIGS. 2 and 5) and a standby position placed apart from the ejecting position (the position shown in FIGS. 1 and 4), and an air nozzle 132 which is attached along a direction of a movement of the base 131 and ejects the air toward the thread inserting hole 111.

The base 131 is formed with a protrusion 131 a protruding in the X-axis direction at a lower end thereof, and slots 131 b, 131 b formed along the Y-axis direction.

The air ejecting unit 130 functions as air ejecting means which faces the thread inserting hole 111 and ejects the air toward the thread inserting hole 111 when the thread hole 21 b of the lower looper 21 is coincident with the thread discharging hole 112.

The threading device 100 is provided with the thread groove 17 (thread introducing means) forming a thread passage through which the lower looper thread T can be inserted. One end of the thread groove 17 is opened toward an outer side of the sewing machine frame M, and the other end thereof is opened above an outlet 132 a of the air nozzle 132. The lower looper thread T is inserted from the one end of the thread groove 17, which is opened toward the outer side of the sewing machine frame M, and is pulled from the other end. The pressurized air from the air ejecting unit 130 is ejected toward the lower looper thread T, whereby the lower looper thread T is inserted into the thread inserting hole 111.

(Air Supplying Means)

The air pump 140 includes an corrugated portion 141 which is extensible and has a hollow structure, and a lever portion 142 which is coupled to one end of the corrugated portion 141 and is operable to compress the corrugated portion 141. The other end of the corrugated portion 141 is connected to the air nozzle 132 through an air tube 143.

Accordingly, when the lever portion 142 is operated to compress the corrugated portion 141, the air inside the corrugated portion 141 is fed to the air nozzle 132 through the air tube 143 and is ejected from the outlet 132 a at an tip portion.

(Air Ejection Moving Means)

The air ejection moving mechanism 150 includes a support member 151 which is fixed to the sewing machine frame M and supports the base 131, and an operation lever 4 operable to move the air ejecting unit 130 between the ejecting position, which is close to the thread inserting hole 111, and the standby position placed apart from the ejecting position (see FIG. 1). The operation lever 4 (a moving member) or the air ejecting unit 130 may be moved by means of a solenoid or a stepping motor.

The support member 151 has two protrusions 151 a, 151 a protruding in the X-axis direction. The protrusions 151 a, 151 a are provided side by side along the Y-axis direction. The each of the protrusions 151 a, 151 a is inserted into the respective slots 131 b, 131 b of the base 131 so that the air ejecting unit 130 is supported so as to be slidable along the Y-axis direction.

The operation lever 4 is fixed at a central portion of the base 131, and the base 131 is moved in the Y-axis direction in accordance with the movement of the operation lever 4. The operation lever 4 is movably engaged with a groove 8 formed on the sewing machine frame M so that a user can move the air ejecting unit 130 in the Y-axis direction by operating the operation lever 4.

(Interlocking Mechanism)

The interlocking mechanism 160 of the sewing machine 1 according to the exemplary embodiment will be described in detail below.

The interlocking mechanism 160 includes a coupling member 161 which couples the thread guide lever 121 of the thread pipe moving mechanism 120 and the base 131 of the air ejecting unit 130.

As shown in FIG. 3, the coupling member 161 is formed from a rectangular plate member having an almost U shape when seen on a plane, and is disposed in a lower part of a bed portion such that a longitudinal direction thereof is set along the Y-axis direction. The coupling member 161 is formed with slots 161 c extending in the Y-axis direction on respective sides in the longitudinal direction thereof. Protrusions 162 a protruding from an upper surface of a base 162, which is screwed onto the sewing machine frame M, are inserted in the respective slots 161 c from below. Accordingly, the coupling member 161 is supported on the base 162 via the slots 161 c and the protrusions 162 a so that it is slidable in the Y-axis direction with respect to the sewing machine frame M.

One end of the coupling member 161 (a left end in FIG. 3) is upwardly bent, and is formed with the coupling groove 161 a having an almost U-shape that is opened upward. The other end of the coupling member 161 (a right end in FIG. 3) is also upwardly bent, and is formed with a coupling hole 161 b extending in a vertical direction. In an assembled state of the sewing machine 1, the coupling shaft 123 b which couples the thread guide lever 121 and the switching lever 123 is inserted in the coupling groove 161 a, while the protrusion 131 a protruding in the X-axis direction on the lower end of the base 131 is inserted in the coupling hole 161 b. Accordingly, the thread guide lever 121 coupled to the one end of the coupling member 161 and the base 131 coupled to the other end of the coupling member 161 are interlocked with each other with respect to a movement in the Y-axis direction.

A distance between the coupling groove 161 a and the coupling hole 161 b, which are positioned on respective ends of the coupling member 161 in the Y-axis direction, is set to be such a length that the tip of the air nozzle 132 (the discharging port 132 a) of the air ejecting unit 130 coupled to the one end is positioned at the ejecting position when the thread discharging hole 112 of the thread pipe 110 is positioned the threading position (see FIG. 5) by means of the thread pipe moving mechanism 120 coupled to the other end. More specifically, the coupling member 161 according to the first exemplary embodiment mechanically couples the thread guide lever 121 of the thread pipe moving mechanism 120 and the base 131 of the air ejecting unit 130, and functions as interlocking means for interlocking the thread pipe moving mechanism 120 and the air ejecting unit 130 such that the air ejecting unit 130 is positioned at the ejecting position when the thread discharging hole 112 of the thread pipe 110 is positioned at the threading position.

Operation of Sewing Machine

Next, description will be given to an operation of the sewing machine 1 according to the first exemplary embodiment.

When changing the lower looper thread T, firstly, the flywheel 7 is rotated to adjust the mark m1 of the flywheel 7 to be coincident with the mark m2 of the sewing machine frame M, thereby moving the lower looper 21 to the rightmost end in the rocking motion.

As shown in FIG. 1, when the operation lever 4 is positioned at its rightmost end, that is, a most retreating position, the coupling member 161 connected to the lower end of the thread guide lever 121 is also positioned at the rightmost end. Therefore, the thread guide lever 121 is rotated in a direction B (a counterclockwise direction) around the fulcrum shaft 122 a so that the thread discharging hole 112 of the thread pipe 110 is positioned at the retreating position (see FIG. 4). On the other hand, the discharging port 132 a on the tip of the air nozzle 132 of the air ejecting unit 130 is positioned in the standby position placed apart from the thread inserting hole 111 as shown in FIG. 1.

When the operation lever 4 is moved to a leftmost end, that is, a most advancing position in FIG. 1 by the operation of the user, the coupling member 161 is also moved to the leftmost end in FIG. 1. Accordingly, the thread guide lever 121 is rotated in a direction A (a clockwise direction) around the fulcrum shaft 122 a so that the thread discharging hole 112 of the thread pipe 110 is positioned at the threading position (see FIG. 5).

Then, when the air pump 140 is operated in a state in which the thread discharging hole 112 is positioned at the threading position, the pressurized air is ejected from the discharging port 132 a on the tip of the air nozzle 132, whereby the lower looper thread T inserted into the thread pipe 110 from the thread inserting hole 111 is discharged from the thread discharging hole 112, and is thus inserted into the thread hole 21 b of the lower looper 21.

After the lower looper thread T is inserted through the lower looper 21, the operation lever 4 is moved to a right side so that the thread pipe 110 is moved to the retreating position and the air ejecting unit 130 is moved to the standby position.

Advantage of First Exemplary Embodiment

As described above, according to the sewing machine 1 of the first exemplary embodiment, when the thread discharging hole 112 of the thread pipe 110 is moved to the threading position by means of the coupling member 161, the air ejecting unit 130 is moved to the ejecting position. Similarly, when the air ejecting unit 130 is moved to the ejecting position, the thread discharging hole 112 of the thread pipe 110 is moved to the threading position. Namely, when the operation lever 4 is operated to operate one of the thread guide lever 121 or the air ejection moving means, the other can also be operated at the same time. Thus, an operation for inserting the lower looper thread T through the lower looper 21 is simplified as compared with the background art. In addition, an certain operating procedure is not required. Therefore, the threading operation can easily be carried out. Thus, it is possible to enhance operability of the sewing machine 1.

Second Exemplary Embodiment Whole Structure

Next, a second exemplary embodiment of the invention will be described in detail with reference to FIGS. 6 to 9. In the second exemplary embodiment, the same structures as those in the first exemplary embodiment are indicated with the same reference numerals, and repetitive description will be omitted.

As shown in FIGS. 6 to 8, the second exemplary embodiment is different from the first exemplary embodiment in that an interlocking mechanism 260 includes a stepping motor 270 (an actuator) which drives the interlocking mechanism 260, a spindle sensor 280 (spindle angle detecting means) which detects that a lower shaft 6 is positioned at a predetermined rotating angle, a control portion 50 which controls the stepping motor 270 in accordance with a detection of the spindle sensor 280, and a threading button 290 (input means) from which a starting instruction of a threading operation is input to insert a lower looper thread T into a lower looper 21.

(Interlocking Mechanism)

As shown in FIG. 6, a coupling member 261 is formed with a coupling groove 261 a, a coupling hole 261 b and slots 261 c in the same manner as in the first exemplary embodiment. In addition, linearly arranged tooth portions, i.e. a rack 261 d is provided along an edge which is parallel to a Y-axis direction.

The stepping motor 270 is provided on a side of the coupling member 261, and a pinion gear 271 attached to the stepping motor 270 meshes with the rack 261 d.

The stepping motor 270 is fixed inside a bed portion of a sewing machine frame M. The stepping motor 270 is electrically connected to the control portion 50 (see FIG. 8) and is rotated so as to correspond to a predetermined number of pulses that is output from the control portion 50, thereby providing a reciprocating linear motion in the Y-axis direction to the coupling member 261. A moving distance and a necessary number of pulses (the predetermined number of pulses) that are required to position a thread discharging hole 112 of a thread pipe 110 at a threading position or at a retreating position are previously stored in an ROM 52 (a storage portion) of the control portion 50. In the second exemplary embodiment, the stepping motor 270 functions as a driving source of the interlocking mechanism 260. Therefore, an operating portion corresponding to the operation lever 4 of the first exemplary embodiment is not necessarily required.

As shown in FIG. 7, in the second exemplary embodiment, a shielding plate 6 a is fixed to an end portion of the lower shaft 6 (the spindle) which is rotated by a rotating force applied from a sewing machine motor 5 via a driving belt 9. The shielding plate 6 a is attached to an outer periphery of the lower shaft 6, that is, a part around an axis of the lower shaft 6 so as to be parallel to an X-Z plane, and is rotatable together with the lower shaft 6.

The spindle sensor 280 is fixed at an upper part of the sewing machine frame M. The spindle sensor 280 according to the second exemplary embodiment is a photosensor having a light emitting portion and a light receiving portion, and the shielding plate 6 a to be rotated with the lower shaft 6 is disposed between the light emitting portion and the light receiving portion, whereby the spindle sensor 280 can detect that the lower shaft 6 is positioned at a predetermined rotating angle.

(Operation Panel)

A sewing machine 1 further includes an operation panel 60 for a user to carry out an operation input. Various data and operation signals input to the operation panel 60 are output to the control portion 50. The operation panel 60 includes a liquid crystal display panel (not shown) and a touch panel (not shown) provided on a display screen of the liquid crystal display panel. Various operation keys displayed on the liquid crystal display panel are operated by a touch so that the touch panel detects a position indicated by the touch and outputs an operation signal corresponding to the detected position to the control portion 50.

The operation panel 60 according to the second exemplary embodiment further includes the threading button 290 (the input means) from which an instruction to start the operation for inserting the lower looper thread T through the lower looper 21 is input, and a retreating button 291 from which an instruction to start a retreating operation is input after the threading operation to move an air ejecting unit 230 to a standby position and to move the thread discharging hole 112 of the thread pipe 110 to a retreating position.

When the user presses down the threading button 290 or the retreating button 291, a signal indicating that the corresponding button is pressed down is output to the control portion 50 so that the control portion 50 carries out various controls which will be described below.

(Control System of Sewing Machine)

Next, a structure of the control portion 50 will be described with reference to FIG. 8.

As shown in FIG. 8, driving sources such as the sewing machine motor 5 and the stepping motor 270, a sensor such as the spindle sensor 280, a sewing machine starting pedal 15 and the operation panel 60 are connected to the control portion 50. FIG. 8 shows only a structure that is necessary for the second exemplary embodiment, and other driving sources and sensors may be connected to the control portion 50.

The control portion 50 includes an MPU (Micro Processor Unit) 51 serving as a microcomputer, the ROM (Read Only Memory) 52, an RAM (Random Access Memory) 53, and an EEPROM (Electrically Erasable and Programmable ROM) 54.

A control program for the over-edge sewing machine 1 is stored in the ROM 52. According to the second exemplary embodiment, the ROM 52 stores data on a necessary number of pulses for moving the air ejecting unit 230 from a standby position to a ejecting position, and a necessary number of pulses for moving the air ejecting unit 230 from the ejecting position to the standby position. The RAM 53 is a memory for providing a work area for the MPU 51. Various data on a sewing operation are backuped in the EEPROM 54. The MPU 51 carries out a processing in accordance with the control program stored in the ROM 52.

According to the second exemplary embodiment, when an instruction to start the threading operation is input from the threading button 290, the control portion 50 stops the lower shaft 6 at a predetermined rotating angle based on the detection by the spindle sensor 280, and drives the stepping motor 270 to position the air ejecting unit 230 at the ejecting position. Namely, the control portion 50 functions as ejection control means.

More specifically, when the threading button 290 of the operation panel 60 is pressed down, the control portion 50 stops the lower shaft 6 at an angle (the predetermined rotating angle) at which the lower looper 21 rocking interlockingly with the lower shaft 6 is positioned at one end of the rocking motion (a position shown in FIGS. 4 and 5) based on a detection signal sent from the spindle sensor 280. Subsequently, the control portion 50 outputs pulse signals necessary for moving the thread discharging hole 112 of the thread pipe 110 from the retreating position to the threading position based on the data stored in the ROM 52, and drives the stepping motor 270.

When the retreating button 291 of the operation panel 60 is pressed down, the control portion 50 outputs pulse signals necessary for moving the thread discharging hole 112 of the thread pipe 110 from the threading position to the retreating position based on the data stored in the ROM 52, and drives the stepping motor 270.

Explanation of Operation of Sewing Machine

Next, an operation of the sewing machine 1 according to the second exemplary embodiment will be described with reference to a flowchart shown in FIG. 9.

First of all, when the threading button 290 is pressed down (Step S1), a signal indicating that the threading button 290 is pressed down is output from the operation panel 60 to the control portion 50. Based on the signal, the control portion 50 drives the sewing machine motor 5 (Step S2) and determines whether the lower shaft 6 is positioned at the predetermined rotating angle or not (Step S3).

The predetermined rotating angle may be set to any rotating angle depending on a attaching position of the shielding plate 6 a with respect to the lower shaft 6. According to the second exemplary embodiment, the predetermined rotating angle is set to an angle of the lower shaft 6 at which the lower looper 21 interlocking with the lower shaft 6 is positioned at one end of a rocking motion of the lower looper 21 (at a rightmost end as shown in FIGS. 4 and 5), that is, the angle at which an extended portion 21 a is inserted through loops of needle threads T1, T2 that are formed when needles 3, 3 are lifted upward.

If the lower shaft 6 is not positioned at the predetermined rotating angle (Step S3; No), the control portion 50 continues to drive the sewing machine motor 5 and repetitively executes the determination until the lower shaft 6 is positioned at the predetermined rotating angle. If it is determined that the lower shaft 6 is positioned at the predetermined rotating angle (Step S3; Yes), the control portion 50 stops the sewing machine motor 5 (Step S4), thereby stopping the lower looper 21.

Next, the control portion 50 drives the stepping motor 270 in a direction of an arrow E shown in FIG. 6 (Step S5) to move an air nozzle 132 forward to the ejecting position (Step S6). At the same time, a thread guide lever 121, which is interlocked with the air ejecting unit 230 via the coupling member 261, is rocked in a direction of an arrow A shown in FIG. 5 so that the thread discharging hole 112 of the thread pipe 110 is positioned at the threading position. The stepping motor 270 is driven by pulse signals output from the control portion 50, the number of pulse signals corresponding to a distance for moving the air nozzle 132 from the standby position to the ejecting position (a moving distance), and the number of pulse signals is previously stored in the ROM 52. The control portion 50 stops the stepping motor 270 (Step S7) after rotating the stepping motor 270 by an amount corresponding to the predetermined number of pulses.

A threading operation is carried out after stopping the stepping motor 270 at Step S7, and when the retreating button 291 is pressed down (Step S9), the control portion 50 drives the stepping motor 270 in a direction of an arrow F shown in FIG. 6 (Step S9) to move the air nozzle 132 backward to the standby position (Step S10). At the same time, the thread guide lever 121 which interlocks with the air ejecting unit 230 through the coupling member 261 is rocked in a direction of an arrow B shown in FIG. 4 so that the thread discharging hole 112 of the thread pipe 110 is positioned at the retreating position. The control portion 50 stops the stepping motor 270 after rotating by an amount corresponding to the predetermined number of pulses in the same manner as the forward movement (Step S11), and ends the processing.

Advantage of Second Exemplary Embodiment

According to the sewing machine 1 of the second exemplary embodiment, the thread guide lever 121 supporting the thread pipe 110 and the air ejecting unit 230 can be electrically controlled by driving the stepping motor 270. In addition, they can be controlled at the same time via the coupling member 261. In other words, the coupling member 261 and the actuator (the stepping motor 270) which drives the coupling member 261 enables a simultaneous control of the thread guide lever 121 and the air ejecting unit 230 without increasing much cost. Accordingly, the threading operation can be carried out more easily than in the background art. Thus, the operability of the sewing machine 1 can be enhanced.

Others

As shown in FIG. 10, a guide member 167 (returning means) may be may be fixed and provided in a bed portion of the sewing machine frame M. The guide member 167 positions the thread discharging hole 112 of the thread pipe 110 to the retreating position in accordance with a drive of the sewing machine motor 5. When the sewing machine motor 5 is driven so that the lower looper 21 starts a rocking motion via the lower shaft 6 and the lower looper driving shaft 22, the thread guide lever 121, the middle portion of which is rotatably supported with respect to the lower looper 21, is also rocked together with the lower looper 21. When a protrusion 121 e formed on the thread guide lever 121 abuts against an inclined portion 167 a of the guide member 167, the thread discharging hole 112 is guided to the retreating position along the inclined portion 167 a. Namely, the thread discharging hole 112 of the thread pipe 110 can be moved to the retreating position in accordance with the driving operation of the sewing machine motor 5. Accordingly, even in a case where a user forgets to return the thread discharging hole 112 of the thread pipe 110 to the retreating position after inserting the lower looper thread T through the lower looper 21, for example, it is possible to smoothly move on to a sewing operation. In other words, the user of the sewing machine 1 is not required to carry out a returning operation for returning the thread discharging hole 112 of the thread pipe 110 from the threading position to the retreating position after inserting the lower looper thread T through the lower looper 21. Thus, the threading work can easily be carried out.

According to the second exemplary embodiment, the rack 261 d is provided on the edge of the coupling member 261 so that the coupling member 261 is directly driven by the stepping motor 270. However, it is also possible to employ a structure in which at least one of a base 231 and the thread guide lever 121 is driven by the stepping motor 270, and the base 231 and the thread guide lever 121 is interlocked via the coupling member 261. Moreover, the actuator is not limited to the stepping motor, and may be, e.g., a solenoid.

Furthermore, gears having different rotating ratios or links having different lengths may be provided at a coupling portion of the coupling member 161 (261) and the thread guide lever 121 and/or a coupling portion of the coupling member 161 (261) and the base 131, whereby a moving distance of the thread guide lever 121 and/or a moving distance of the base 131 with respect to a moving distance of the coupling member 161 (261) in the Y-axis direction can be desirably changed.

As a third exemplary embodiment, it is also possible to operate a thread guide lever 121 and an air ejecting unit 130 synchronously by means of separate driving members.

For example, as shown in FIG. 14, a first stepping motor ST1 (a first actuator) is coupled to an operating plate M1 via connecting means R1 such as a rack and a pinion, and rocks the thread guide lever 121. The operating plate M1 is connected to the thread guide lever 121 of thread pipe moving means 120.

As shown in FIG. 15, moreover, a second stepping motor ST2 (a second actuator) is coupled to the base 131 via connecting means R2 such as a rack and a pinion, and reciprocates a base 131.

As shown in FIG. 16, both the stepping motors ST1 and ST2 are controlled by a control portion 50 (interlocking control means) such that the thread pipe moving means 120 and the air ejecting unit 130 are synchronously operated.

While description has been made in connection with exemplary embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modification may be made therein without departing from the present invention. It is aimed, therefore, to cover in the appended claims all such changes and modifications falling within the true spirit and scope of the present invention. 

1. A sewing machine comprising: a looper driving mechanism including a looper, wherein the looper is formed with a thread hole at a tip portion thereof, and the tip portion of the looper is adapted to be inserted into a loop of a needle thread by moving the tip portion back and forth in synchronization with a vertical motion of a needle; a thread path member having one end formed with a thread inserting hole, the other end formed with a thread discharging hole, and a thread path inside which a lower looper thread is able to be inserted; thread path member moving means for moving the thread path member such that the thread discharging hole is moved between a threading position, at which the thread discharging hole becomes coincident with the thread hole of the looper, and a retreating position placed apart from the threading position; air ejecting means for ejecting air toward the thread inserting hole, wherein the air ejecting means is disposed so as to face the thread inserting hole; air supplying means for supplying the air to the air ejecting means; air ejection moving means for moving the air ejecting means between an ejecting position adjacent to the thread inserting hole and a standby position placed apart from the ejecting position; and interlocking means for interlocking the thread path member moving means and the air ejection moving means such that the air ejecting means is positioned at the ejecting position when the thread discharging hole is positioned at the threading position.
 2. The sewing machine according to claim 1, wherein the interlocking means includes: a first actuator which drives the thread path member moving means; a second actuator which drives the air ejection moving means; and interlocking control means for driving the first and second actuators such that the thread path member moving means and the air ejection moving means synchronize with each other.
 3. The sewing machine according to claim 1, wherein the interlocking means includes a coupling member which couples the thread path member moving means and the air ejection moving means.
 4. The sewing machine according to claim 1, wherein the interlocking means includes an actuator which drives at least one of the thread path member moving means and the air ejection moving means.
 5. The sewing machine according to claim 2, wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle, wherein the sewing machine further comprises: input means for inputting an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper; spindle angle detecting means for detecting that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and ejection control means for stopping the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting means and for driving the second actuator to position the air ejecting means at the ejecting position when the instruction to start the threading operation is input from the input means.
 6. The sewing machine according to claim 4, wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle, wherein the sewing machine further comprises: input means for inputting an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper; spindle angle detecting means for detecting that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and ejection control means for stopping the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting means and for driving the actuator to position the air ejecting means at the ejecting position when the instruction to start the threading operation is input from the input means.
 7. The sewing machine according to claim 1, wherein the sewing machine further comprises returning means for positioning the thread discharging hole of the thread path member at the retreating position in accordance with a drive of a sewing machine motor.
 8. A sewing machine comprising: a looper driving mechanism including a looper, wherein the looper is formed with a thread hole formed at a tip portion thereof, and the tip portion of the looper is adapted to be inserted into a loop of a needle thread by moving the tip portion back and forth in synchronization with a vertical motion of a needle; a thread pipe having a thread path inside which a lower looper thread is able to be inserted, wherein the thread path connects a thread inserting hole and a thread discharging hole, and the thread pipe is arranged such that the thread discharging hole is movable between a threading position a threading position, at which the thread discharging hole becomes coincident with the thread hole of the looper, and a retreating position placed apart from the threading position; a thread pipe moving mechanism which is coupled to the thread pipe and is operable to move the thread discharging hole between the threading position and the retreating position; an air ejecting unit which is movable between an ejecting position, at which the air ejecting unit faces the thread inserting hole and ejects air toward the thread inserting hole, and a standby position placed apart from the ejecting position; an air supplying unit which supplies the air to the air ejecting unit; a air ejection moving mechanism which is coupled to the air ejecting unit, and operable to move the air ejecting unit between the ejecting position and the standby position; and an interlocking mechanism operable to interlock the thread pipe moving mechanism and the air ejection moving mechanism such that the air ejecting unit is moved from the standby position to the ejecting position when the thread discharging hole is moved from the retreating position to the threading position.
 9. The sewing machine according to claim 8, wherein the interlocking mechanism includes: a first actuator which drives the thread pipe moving mechanism; a second actuator which drives the air ejection moving mechanism; and an interlocking control portion operable to drive the first and second actuators such that the thread pipe moving mechanism and the air ejection moving mechanism synchronize with each other.
 10. The sewing machine according to claim 8, wherein the interlocking mechanism includes a coupling member which couples the thread pipe moving mechanism and the air ejection moving mechanism.
 11. The sewing machine according to claim 8, wherein the interlocking mechanism includes an actuator which drives at least one of the thread pipe moving mechanism and the air ejection moving mechanism.
 12. The sewing machine according to claim 9, wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle, wherein the sewing machine further comprises: an input portion form which an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper is input; a spindle angle detecting sensor which detects that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and an ejection control portion which stops the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting sensor and drives the second actuator to position the air ejecting unit at the ejecting position when the instruction to start the threading operation is input from the input portion.
 13. The sewing machine according to claim 11, wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle, wherein the sewing machine further comprises: an input portion form which an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper is input; a spindle angle detecting sensor which detects that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and an ejection control portion which stops the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting sensor and drives the actuator to position the air ejecting unit at the ejecting position when the instruction to start the threading operation is input from the input portion.
 14. The sewing machine according to claim 8, wherein the sewing machine further comprises a guide member which positions the thread discharging hole at the retreating position in accordance with a drive of a sewing machine motor. 